Each incoming request is processed by a specific worker, i.e. a
thread in the running program. Total number of running workers is
controlled by three configuration parameters. WorkerMinCount
defines the minimum number of workers that should always be running
(5, by default). Another parameter, WorkerMaxCount sets the
upper limit on the number of running workers (it defaults to 128).
At each given moment, a worker can be in one of two states: idle
or active (processing a request). If an incoming request
arrives when all running workers are active, and total number of
workers is less than WorkerMaxCount, a new thread is started and
the new request is handed to it. If the number of active workers has
already reached maximum, the new request is added to the request
queue, where it will wait for a worker to become available to
process it.
The third parameter, WorkerIdleTimeout, specifies maximum time
a thread is allowed to spend in the idle state. If a worker
remains idle longer than that and total number of workers is greater
than the allotted minimum (WorkerMinCount), this idle worker is
terminated.